Demo app on Netlify is not working

[jaballogian]

I want to see some demo from Google Maps API especially for how to draw a resizable circle using Drawing Manager and search to places using Standalone Search Box (please correct me if I'm wrong).
I found the demo here https://react-google-maps-api-gatsby-demo.netlify.app/ but the demo returned an error.

It said that There has been an Error with loading Google Maps API script, please check that you provided correct google API key but I already provided the API key to the demo app and to this documentation https://react-google-maps-api-docs.netlify.app/.

The API key doesn't strict any application and already allows some Google Maps API like shown in this image below:

I tried to create a simple react app using original react app template then add a Google Maps into the app and attached the same API key to my app, the Google Maps showed.

So how could I do to see the demo app on the Netlify?

[jaballogian]

Fortunately, if I insert the API key to the documentation https://react-google-maps-api-docs.netlify.app/, I could see the demo in the documentation for each sample.